The United States marks its waters to assist mariners, mark isolated dangers, enable pilots to follow channels, and help ships pilot coastal waters. The system of marking is known as the U.S. Aids to Navigation System (AToN). AToN relies primarily on buoys and beacons as marking devices, but also employs lights, lightships, radio beacons, fog signals, and marking indicia. The marking indicia include various arrangements of colors, shapes, numbers, and light characteristics that provide additional information about navigable channels, waterways and nearby obstructions.
“Buoys” are floating objects that are anchored. Their distinctive shapes and colors communicate their purpose and how to navigate around them. “Beacons” are structures, permanently fixed to the sea-bed or land. They range in size from light houses to single-pile poles.
The United States Coast Guard (the “Coast Guard”) maintains AToN and expends a great deal of resources inspecting, retrieving and overhauling buoys. Conventionally, the Coast Guard retrieves buoys for depot level maintenance at set time intervals (usually nine years).
A set interval for depot level maintenance, however, is inefficient. Buoys in different environments corrode at different rates. Many variables affect the corrosion rate, so the amount of corrosion for any given buoy over the maintenance time interval is considered unpredictable. Periodic depot level maintenance for any given buoy may be premature, timely, or too late. When the buoy needs no substantial maintenance, the depot work is premature. When the buoy is beyond repair, the work is too late. Timely buoy maintenance performed as needed would be more efficient than performing maintenance at predetermined intervals.